The present invention relates to a two-sided electronic auction scheme that permits multiple sellers and buyers distributed on a communication network to hold auctions by electronic means, an apparatus for the auction scheme, and a recording medium on which there are recorded programs for implementing the auction scheme.
Two-sided auction schemes, by which multiple sellers and buyers submit their desired selling/purchase prices for a certain kind of goods put on sale and trade, are called double auctions and have been widely used in stock, bond and foreign exchange markets. One of the conventional double auction protocols is a PMD protocol (R. P. AcAfee, “A Dominant Strategy double Auction,” Journal of Economic Theory, vol.56, pp.434-450, 1992). The PMD protocol will be described below.
FIG. 1 is a diagrammatic showing of an electronic double auction system based on the PMD protocol, in which multiple seller apparatuses 1-1, . . . , 1-n and multiple buyer apparatuses 2-1, . . . , 2-m are distributed communication network 11, to which an auctioneer apparatus 12 is connected. That is, assume that m buyers and n sellers are present on the communication network 11. Further, assume that each buyer demands only one unit of a single kind of goods and that each seller possesses one unit of a single kind of goods.
The m buyers use their apparatuses 2-1, . . . , 2-m to send applications for bidding to the auctioneer apparatus 12 together with their evaluation values b1, . . . , bm (which are the highest possible purchase prices, not necessary true), and the n sellers use their apparatuses 1-1, . . . , 1-n to send applications for bidding to the auctioneer apparatus 12 together with their evaluation values s1, . . . , sn (which are the lowest possible selling prices, not necessarily true).
As shown in FIG. 2, upon receiving the applications for bidding from the seller apparatuses 1-1, . . . , 1-n and the applications for bidding from the buyer apparatuses 2-1, . . . , 2-m (step S1), the auctioneer apparatus 12: stores the sellers and buyers of the applications received and their evaluation values in a storage part (step S2); makes a check to determine if the deadline for applications has passed (step S3); and if not, returns to step S1 to wait for applications to come. It is predetermined that the term for accepting the applications, for example, runs from a certain time in the morning of a weekday to a certain time in the morning; the sellers and buyers send their applications for bidding to the auctioneer apparatus 12 by the deadline.
Upon expiration of the term for application, the auctioneer apparatus 12 reads out the evaluation values of all the buyers from the storage part and sorts their declared evaluation values b1, . . . , bm in decreasing orderb(1)≧b(2)≧ . . . ≧b(m) (step S4), and reads out the sellers declared evaluation values s1, . . . , sn from the storage part and sort them in increasing orders(1)≦s(2)≦ . . . ≦s(n) (step S5). In the above, b(i) represents the i-th largest one of the buyers' declared evaluation values and s(i) represents the i-th smallest one of the sellers' declared evaluation values. When multiple evaluation values are equal (in the case of a tiebreak), they are sorted randomly (by lot or the like).
To simplify the protocol description, let b(m+1) represent the smallest possible evaluation value of the buyers (e.g., 0) and s(n+1) represent the largest possible evaluation value of the sellers (e.g., one billion dollars). Further, assume that b(m+1)<s(n+1) holds.
A search is made for k such that b(k)≧s(k) and b(k+1)<s(k+1) hold (step S6). If this k is found, a maximum of k trades is possible since the first to k-th evaluation values of the buyers are equal to or larger than the evaluation values of the sellers. If the k is not found, the auctioneer notifies every bidder or participant of failure in trading (step S12), and put an end to the current session of auction.
A candidate p0 of the trading price is defined as given below and the price p0 is calculated (step S7).P0=(b(k+)+s(k+1))/2
The protocol is described as follows.
A check is made to see if s(k)≦p0≦b(k) holds (step S8).
Case (a): If s(k)≦p0≦b(k) holds, the first to k-th buyers and sellers trade at the price p0. That is, the auctioneer apparatus 12 sends to each of these buyers' and sellers' apparatuses a notification that the trade will be made at the price p0 (step S9).
Case (b): If s(k)≦p0≦b(k) does not hold, the first to (k−1)-th buyers and sellers trade. All of the k−1 buyers pay b(k), and the k−1 sellers all receive s(k). The auctioneer apparatus 12 sends to each of the buyers' apparatuses concerned a notification that the trade succeeds at b(k), and to each of the sellers' apparatuses a notification that the trade succeeds at s(k) (step S10).
In either of the cases (a) and (b), the auctioneer notifies unsuccessful buyers and sellers of failure in trading (step S11).
When the condition in step S8 does not hold, that is, in the case of (b), since the price b(k) to be paid by the buyer is equal to or higher than the price s(k) to be received by the seller, the difference (k−1)(b(k)−s(k)) is left over. Assume that the auctioneer receives this difference.
It is known in the art that when no false-name bids are submitted, the utility of each bidder can be maximized by bidding a correct evaluation value, i.e. the largest possible evaluation value indicating that the buyer has no intention of paying higher prices, and the smallest possible evaluation value indicating that the seller has no intention of trading at lower prices. This property is called incentive compatibility. When the incentive compatibility holds, electronic auctions can easily be held without the need for hiding the bid value of every bidder from other participants as in ordinary electronic auction schemes.
Electronic auctions using telecommunication systems, typified by the Internet, permit a single bidder to easily submit multiple bids using multiple names (for example, different electronic mail addresses). This is called false-name bidding.
If the false-name bidding is possible, the PMD protocol doe not satisfy the incentive compatibility as described below.